A semiconductor device includes a foundation layer and a transistor layer. The foundation layer is based on single-crystalline silicon carbide and includes a current propagation region of a first conductivity type and a non-depletable shielding structure of a second conductivity type. The transistor layer is based on epitaxially grown single-crystalline silicon carbide and includes a transistor cell (TC) configured to control a current through the current propagation region. The transistor layer is formed on the foundation layer after formation of the shielding structure in the foundation layer such that an epitaxial interface forms between the transistor foundation layer and the layer. The current propagation region extends from the epitaxial interface between neighboring partial regions of the shielding structure. Along a vertical line orthogonal to the epitaxial interface and through a pn junction between the shielding structure and a region of the first conductivity type in the transistor layer, a net dopant concentration changes by at least 1e17 1/cm.sup.3 per 0.1 m at the position of the pn junction.

A semiconductor device includes a drift layer of a first conductivity type, a channel layer of a second conductivity type, a source layer of the first conductivity type, a gate electrode, a source electrode, and a drain electrode. In a case where an impurity concentration of the drift layer is different in the drift layer, an integral value of an electric field applied to the drift layer is set as a withstand voltage value, and an integral value of an electric field in a case where the impurity concentration of the drift layer is constant in the drift layer is set as a reference value, (the withstand voltagethe reference value)/the reference value is equal to or greater than 0 and equal to or less than 0.32.

An impurity region of P-type that the field effect transistor of the nitride semiconductor device includes has a peak position at which concentration of P-type impurities reaches a maximum at a position located away from an interface with a gate insulating film. The impurity region has an inflection point at which concentration of the P-type impurities changes from increase to decrease toward the interface or a rate of decrease in the concentration of the P-type impurities increases toward the interface at a position located between the interface and the peak position.

The present invention involves a power device and a manufacturing method thereof. The method comprising steps of providing a semiconductor substrate, growing an epitaxial layer on the semiconductor substrate, forming an insulating layer on the epitaxial layer, forming a metal mask layer on the insulating layer, and performing an ion implantation process from above the metal mask layer on the epitaxial layer. The metal mask layer includes an ion implantation blocking region and an ion implantation penetration region.

A manufacturing method of a semiconductor device includes the following steps. A base region is formed in a substrate. A protective layer is formed on the substrate and covers the base region. First and second sacrificial layers are formed on the substrate and cover the protective layer. A source region, a well region, and a junction field effect transistor (JFET) region are formed in the substrate. When the source region, the well region, and the JFET region are formed in sequence, the source region and the well region are formed by the first sacrificial layer, and the JFET region is formed by the second sacrificial layer. When the JFET region, the well region, and the source region are formed in sequence, the JFET region is formed by the first sacrificial layer, and the well region and the source region are formed by the second sacrificial layer.

A semiconductor device includes a chip formed by a wide bandgap semiconductor and having a principal surface on which a semiconductor region of a first conductivity type is formed, a base impurity region of a second conductivity type formed in a surface layer portion of the semiconductor region, a first impurity region formed in a surface layer portion of the base impurity region, and a second impurity region of a conductivity type opposite to that of the first impurity region formed in the surface layer portion of the base impurity region, the second impurity region being adjacent to the first impurity region in a first direction, wherein the second impurity region is formed in a band shape extending in a second direction orthogonal to the first direction, and includes a projection portion selectively protruding toward the first impurity region in the first direction.

A semiconductor device includes, within an outer peripheral region: an outer peripheral p-type layer; an outer peripheral n-type layer positioned on an outer peripheral side relative to the outer peripheral p-type layer with a space from the outer peripheral p-type layer; a high breakdown voltage p-type layer arranged to include a portion of an upper surface of a semiconductor substrate located between the outer peripheral p-type layer and the outer peripheral n-type layer; a drift n-type layer extending up to the upper surface between the high breakdown voltage p-type layer and the outer peripheral n-type layer; a protective electrode disposed above the high breakdown voltage p-type layer via an interlayer insulating film and electrically connected to an upper electrode; and a semi-insulating film covering the upper surface between the protective electrode and the outer peripheral n-type layer and having a resistivity of 110.sup.8 .Math.cm to 110.sup.14 .Math.cm at 25 C.